ESR1 and breast carcinoma: Recent work by Li et al. reported that nuclear p21-activated kinase 4 (nPAK4) co-localized with endogenous ER-alpha (ERα) in the nucleus of ER+ MCF7 and ZR-75-30 breast cancer cells, resulting in the recruitment of the PAK4-ERα complex to estrogen response elements (EREs) upstream of the LIFR promoter, inhibiting the expression of LIFR and promoting bone metastasis [86].